Mineral wool-producing system and method of producing mineral wool



1967 G. SAGEN ETAL 3,303,009

MINERAL WOOLPRODUCING SYSTEM AND METHOD OF PRODUCING MINERAL WOOL FiledSept. 10, 1965 \NVENTOR Kane BY w

ATTORNEY United States Patent 3,303,009 MINERAL WOOL-PRODUCING SYSTEMAND METHOD OF PRODUCING MINERAL WOOL Gunnar Sagen, Copenhagen, and KarlEjvind Haulund Christensen, Roskilde, Denmark, assignors to 1/8 Kahler &(10., Hedehusene, Denmark, a Danish firm Filed Sept. 10, 1963, Ser. No.307,914 6 Claims (Cl. 658) The present invention relates to a mineralwool-producing system in which a melt of mineral material, preferably amelt of slag or rock is ejected from the peripheral surface of at leastone rotor constituting a part of a rotor system comprising at least tworotors of which at least one receives the melt as a liquid stream whichmay be poured on to the rotor in question directly from a meltingfurnace, for instance a cupola and of which at least one rotorexclusively receives melt that has been ejected thereto from one or moreother rotors.

In its simplest form a system of this kind operates by melting a mixtureof minerals such as slag and rock in a suitable furnace, for instance acupola, pouring the melt into a drain or chute from which the melt isapplied to the peripheral surface of a rotor by gravity with the linearvelocity determined by inter alia the viscosity of the melt and thedistance between the chute and the rotor. From the rotor receiving themelt, most of the melt received is ejected with greater velocity thanthat with which it was received and in such direction that it isreceived by the peripheral surface of another rotor, generally one withfaster rotation, upon which it is distributed. From both rotors-althoughonly sparsely from the first rotor--the melt is ejected partially in theform of fibres which are then carried away from the system of rotors bya current of gaseous medium introduced from behind the rotors andsedimented by the gaseous carrier being removed by being drawn throughan advancing perforated support such as a band or wire gauze, on thesurface of which the fibres are retained and form a layer of wool.

The yield and fineness of the fibres obtained from a rotor is, however,determined partially by the speed with which the rotor rotates,partially by the degree to which it has been achieved to accelerate thelayer of melt present on the rotor up to the peripheral velocity of therotor prior to its ejection thereform. If the linear velocity at whichthe melt is applied is too small it will mash or smear insufiiciently onthe rotor surface, and the thickness of the layer thereby formed willaccordingly be too great which results in that the greater part of themelt is ejected prior to having obtained the peripheral velocity of therotor. ever, sufiiciently to obtain the peripheral velocity of the rotorbefore being ejected, and for this part of the melt the said velocitydetermines the length and thickness of the fibres.

In this simple system of two rotors, the first rotor may be consideredas the melt application device for the second rotor. It is not intendedthat the first rotor should form fibres because the relatively smallvelocity of this rotor causes the fibres to be too coarse. On the otherhand the functioning of the first rotor as application device is alsofar from ideal. In spite of the low velocity of the melt on applicationthere is a certain adhesion of the melt to the rotor which, although itis weak, causes two inconveniences. First it causes the formation ofcoarse fibres, and secondly it causes the direction in which the cascadeof melt delivered from this rotor is ejected is not sufiicientlydistinct. On the contrary, there is a tendency against the solidifieddrops to be ejected with or without adherent fibres along the wholeperipheral surface. In the same system the second rotor may beconsidered as the spinning device. However, the linear Another part ofthe melt adheres, howvelocity of the melt that can be obtained by usinga single rotor for the application device is too small to secure acomplete smearing or mashing on the peripheral surface of the secondrotor. Accordingly, the melt transferred to this rotor will onlypartially obtain the peripheral velocity of the rotor and consequently asubstantial part of the melt will be used up in forming coarse fibres orget lost in the form of greater and smaller drops leaving the rotor as amore or less indistinct cascade.

It follows from what has been said above, that when using three or fourrotors it is possible to obtain better yields of mineral wool whentherotors are placed relative to each other in such a way that the part of.the melt ejected in the form of a more or less distinct cascade ofdrops adjacent to the place, where the melt has impinged on the rotor inquestion, is received by a subsequent rotor. Each previous rotor may inthis case be considered the application device of a subsequent rotor andfunctions simultaneously as a spinning device. The linear velocity withwhich the melt is applied is thus increasingly greater and anincreasingly greater part adheres to the receiving rotor and isdelivered as increasingly fine fibres. A disadvantage in systems of thiskind where more than two rotors are used is that fibres ejected fromparts of the peripheral surfaces adjacent to each other tend to collideand may give rise to damaging of the individual fibres and to theformation of hard felted fibre nuclei the presence of which in the woolproduces a non-uniform specific Weight of the product.

There is, however, a fiberizing system of the kind in quest-ion, bywhich a particularly homogeneous 'wool can be obtained, although withcomparatively small yieldsby using only two rotors.

In this rotor system the two rotors are placed at a smal horizontalmutual distance and driven with opposite direction of rotation. Theincoming stream of melt is caused to impinge on the peripheral surfaceof one of the rotors at a point a little above the point, where thedistance is minimum. Consequently, most of theincoming melt is repelledat increased velocity in such direction that is can be received from theother rotor. Part of the melt thus received is again repelled to thefirst rotor, another part adhering to rotor 2 and being ejected asmineral wool from the rest of the peripheral surface thereof. The meltthus repelled from the second rotor adheres to the first rotor and isejected therefrom. To a certain degree repeated injections andrejections will probably occur within the interstice between the tworotors where they are closest to each other, which contributes to thegradual increase in velocity of the melt retained on the cylindricsurfaces. A considerable part of the melt, however, does not succeed inhaving the opportunity to partake in the ejections and rejections and,consequently, does not adhere to any of the rotors. Such melt escapes inthe form of a more or less compact or concentrated jet through theinterstice between the rotors. This part of the melt solidifies in theair and is lost. In this tworotor-system the ejection of fine fibres ison the whole finished before the melt has passed through a wholerotation so that, consequently, collision of ejected fibres will hardlyoccur. Accordingly, the formation of nuclei is avoided and thehomogeneity is greater than the case of systems comprising more than tworotors, whereas the yield and the rate of production is generally small.

It has been found according to the present invention that improvedresults both with respect to the yield of fibres, productivity andhomogeneity of the fibres as a result of the formation of tight nucleibeing avoided can be obtained so as to obtain wool with evendistribution of the weight per volume within the fibrous product. Thisis achieved by a system of the kind described above in which mineralwool is produced by ejection of a melt from the peripheral surface of atleast one rotor forming part of a system of at least two rotors of whichat least one receives melt as an incoming stream and at least oneexclusively receives melt that has been ejected from other rotors, thefeature characterizing the present invention being that a slip-producingagent is applied to the first named rotor or rotors prior to theapplication of the melt thereon. The term, slip-producing (orslip-increasing) agent is used here and in the following to designate anagent which substantially prevents or greatly reduces the adhesion ofthe melt to the rotor receiving it which would occur if such agent wasnot present. For brevity the term slip-producing will generally be usedmeaning an agent producing a slip which would not be present if theagent was not applied.

By applying the slip-producing agent it is obtained that the incomingmelt when reaching the first rotor is rapidly and totally rejected atincreased velocity in the form of a directed cascade of drops. Thus, themelt. does notfollow the rotation of the first rotor to any substantialdegree and, accordingly, this rotor will produce no wool and cannot giverise to the formation of small solidified drops, coarse fibres or fibrecollisions.

As a slip agent there can be used according to the present invention ahigh-boiling oil, such as steam cylinder oil. This oil will partlyevaporate, partly it may char producing in that case a thin layer ofcarbon upon the first rotor. Carbon produced .in that way acts -as slipagent itself, and furthermore by degree it burns under the influence ofthe heat of the melt. Consequently, it does not tend to accumulate andform scales. Any tendency in this direction can moreover be controlledby using oil having the necessary resistance against carbonization andby controlling .the amountof oil, so that all the oil has time toevaporate d-urinig a single rotation of the rotor. The circumstance thatthe carbonization products which may be formed act themeselves asslip-producing agents invite the use of a current of finely distributedcarbon as slip-producing agent. carbon may be used in suspension in asuitable fluid, such as oil or water.

In an embodiment of the invention which is illustrated in the drawingwhich shows diagrammatically seen from the side, a system whichcomprises four rotors the two upper of which receive slip-producingagent (not shown) and producing no wool and the two lower of whichreceive no such agent and produce wool (not shown), the above describedsystem is used. I The melt rejected from the first rotor is received'byanother rotor placed close to the first one, and having the samefunctioning and preferably opposite direct-ion of rotation. From thissecond rotor it is transferredto the rotor or the rotors the function ofwhich is to produce the wool. The second rotor receives alsoslip-producin-g agent either directly applied simultaneously with thecascade from the first rotor, or slipproducing agent still presentcascade of melt received from the first rotor. Accordingly, it rapidlyrejects the melt received at further increased velocity in the form of adirected cascade of drops. In all circumstances the amount ofslip-producing agent applied must be controlled so that noslip-producing agent leaves the second rotor in active state in order tosecure that fiberization can occur on the subsequent rotor or rotors.

The fiberization is hereafter carried out in known way, the ejectedcascade being received by a rotor from the surface of which fibres areejected in normal way. This rotor is capable of yielding a high andhomogeneous production of fibres because the melt received has a greatlinear velocity and obtains by smearing a high degree of contact withthe peripheral surface. In order to further increase the productioncapacity a fourth rotor may be placed adajacent to the third one at asmall distance therefrom, in order to receive rejected drops of Suchfinely distributed.

melt therefrom and effect the fiberization thereof. This system of fourrotors is particularly advantageous when using the present inventionbecause the precise receipt of the melt on the third rotor makes itpossible to place the point where this melt is received rather close tothe fourth rotor thereby utilizing practically the whole of theperipheral surface of the third rotor for fiberization and avoiding therisk of fibre collision.

Between the set of rotors consisting of the two first rotors and the setof rotors consisting of the two latter rotors the distance may berelatively great for instance exceed 8 centimetres in each point of theperipheral surface of the rotors. The latter set of rotors is therebycaused to work in a similar way to the rotors of a tworotor-system in sofar as there will be only a very slight possibility of collision betweenfibres ejected and between the fibres and the incoming melt orsolidified drops, since in the interstice between the four rotorspractically no other material occurs than the cascades of melttransferred from the first set of rotors to the second one and transfersbetween the two rotors of the second set. This is due to the fact thatpractically the whole amount of fibres produced by the third and fourthrotors is ejected before each of the rotors has made a single rotationand to the fact that the first and second rotors do .not produce fibresbut only the said cascades. Both rotors of the second set furthermorefunction with greater effectivity being capable of forming finer fibresand less solidified drops, socalled beads, because the linear velocitywith which the melt is applied to the first of these rotors is greaterthan in a two-rotor-system.

Thus, according to the present invention a particularly advantageousembodiment is characterized in that the melt from the second rotor isdirected down against two rotors with opposite direction of rotationplaced below the first and having downwardly directed motion of theperipheral surface .parts turning towards each other, so that it reachesat least one of the rotor surfaces at a point of the peripheral surfacewhich is close to the point Where the two lower rotors are closest toeach other.

The systems comprised by the invention are, however, not bound to theembodiment described above in detail, but comprise any system in which aslip-producing agent is applied to a rotor receiving the melt as anincoming fiuid'stream, and in which there is furthermore at least onerotor to which the melt rejected from the first one is transferred and.which does not receive slip-producing agent, but functions as afiberizing rotor. Thus incoming melt in the form of a stream of fluidmay be applied to more than one rotor, for instance to two rotors, bothof which receive slip-producing agent and both of which being in aposition to provide one or more fiberizing rotors with rejectedmaterial, or in a position to cooperate in applying melt to one or moresubsequent rotors functioning mainly as fibre-forming rotors.Furthermore, there may be more than two rotors placed in cascadingsequence, the melt being transferred from one of such rotors to theother at a constantly increasing velocity, one or more of which receiveslip-producing agent, preferably in gradually reduced amount.Slip-producing agent may be applied as a coherent stream or,advantageously, in atomized form by means of suitable jets.

We claim:

1. Mineral wool producing rotor system consisting of at least one rotorhaving a peripheral surface, means for supplying a stream of moltenmineral melt to said peripheral surface and at least one further rotorreceiving mineral melt ejected from another rotor and rotating at suchvelocity that it produces a fine wool, in which system at least onerotor has means for applying to its peripheral surface, prior to theapplication of the mineral melt, an amount of a slip-producing agent,and at least one other rotor which receives mineral melt ejected fromanother one as above set fort-h, and rotates at a speed at 5 which finewool can be produced, has no slip-producing agent applied thereto.

2. Mineral wool producing rotor system according to claim 1 in which thefirst rotor transfers melt to another rotor placed adjacent thereto andmeans to supply said last-named rotor with slip-producing agent and athird rotor receives the melt from the second rotor and works withoutslip-producing agent.

3. Mineral wool producing rotor system according to claim 1 in which themelt transferred to a rotor Working without slip-producing agent from arotor working with means for supplying slip-producing agent is partiallytransferred to a further rotor working without slip-producing agent.

'4. Method of producing mineral wool by acceleration of movement ofmineral wool on revolving surfaces and transferring melt from onerotating surface to another in which the melt is first applied from aliquid stream to revolving surfaces wetted by a slip-producing agentwhich reduces adhesion of the melt to the surfaces and is repelled fromsaid surfaces to rotating surfaces to which no slip-producing agent isapplied and from which it is ejected in the form of fine wool.

5. The method of claim 4 in which the slip-producing agent is acar-bonization agent.

'6. The method of claim 4 in which the slip-producing agent is a highboiling oil.

References Cited by the Examiner UNITED STATES PATENTS 2,520,169 8/1950Powell 658 FOREIGN PATENTS 149,397 2/ 1952, Australia.

DONALL H. SYLVESTER, Primary Examiner.

R. L. LINDSAY, Assistant Examiner.

1. MINERAL WOOL PRODUCING ROTOR SYSTEM CONSISTING OF AT LEAST ONE ROTORHAVING A PERIPHERAL SURFACE, MEANS FOR SUPPLYING A STREAM OF MOLTENMINERAL MELT TO SAID PERIPHERAL SURFACE AND AT LEST ONE FURTHER ROTORRECEIVING MINERAL MELT EJECTED FROM ANOTHER ROTOR AND ROTATING AT SUCHVELOCITY THAT IT PRODUCES A FINE WOOL, IN WHICH SYSTEM AT LEST ONE ROTORHAS MEANS FOR APPLYING TO ITS PERIPHERAL SURFACE, PRIOR TO THEAPPLICATION OF THE MINERAL MELT, AN AMOUNT OF A SLIP-PRODUCING AGENT,AND AT LEAST ONE OTHER ROTOR WHICH RECEIVES MINERAL MELT EJECTED FROMANOTHER ONE AS ABOVE SET FORTH, AND ROTATES AT A SPEED AT WHICH FINEWOOL CAN BE PRODUCED, HS NO SLIP-PRODUCING AGENT APPLIED THERETO. 4.METHOD OF PRODUCING MINERAL WOOL BY ACCELERATION OF MOVEMENT OF MINERALWOOL ON REVOLVING SURFACES AND TRANSFERRING MELT FROM ONE ROTATINGSURFACE TO ANOTHER IN WHICH THE MELT IS FIRST APPLIED FROM A LIQUIDSTREAM TO REVOLVING SURFACES WETTED BY A SLIP-PRODUCING AGENT WHICHREDUCES ADHESION OF THE MELT TO THE SURFACES AND IS REPELLED FROM SAIDSURFACES TO ROTATING SURFACES TO WHICH NO SLIP-PRODUCING AGENT ISAPPLIED AND FROM WHICH IT IS EJECTED IN THE FORM OF FINE WOOL.